Baking of several particle systems
First off, particle systems are responsible for emitting particles, they have nothing to do with any smoke or fire simulations; on the other hand, smoke simulation is used for emitting smoke, not for particles. Particle system can be used as emitter for smoke (instead of actual mesh), - but their data is different and you can't bake smoke simulation from particle system panel (unless baking everything, see below).  

Hence there is Bake button for baking in their options. It will work per each physics simulation - each smoke / fire sim will be baked from its domain, particle systems - from their options per each particle system, same for dynamic paint etc. With this way you'll bake them one by one.



The only way which is independant on these options is to bake all physics at once - with Bake All Dynamics button which will bake everything you have to bake in scene:


  Bake All Dynamics
      Bake all physics systems in the scene, even those of different types. Useful for baking complex setups involving interactions between different physics types.


Note that it may last longer than you expected (because of amount of data to compute).